Internal endless films are generally manually removed from cylindrical molds or female mandrels (the terms will be used interchangeably here) on which they are formed. The separation is initiated with a sharp object such as a razor blade corner, knife edge or finger nail. The process is difficult, time consuming and may damage both the film and the mandrel. After the initial separation, an entire hand and arm are forced between the film and the mandrel axially to separate the film from the mandrel. The film is then axially folded in half and then into quarters and removed from the inside of the mandrel by hand.
Extensive handling of an endless film may damage the film, especially when a very thin film is to be removed. Fingerprints, perspiration and oils may contaminate the film, rendering it damaged and unusable. Endless film to be used in electrophotographic and electrostatographic applications is especially sensitive to such damage. Many other applications require a film virtually free of defects and contaminants. Other problems with such manual methods include the formation of creases, tears and scratches in the film. The process is also slow and costly due to the manual labor involved.
U.S. Pat Nos. 3,947,208, 3,966,386 and 4,795,124 and Japanese Publication No. 47-19338 disclose various methods of removing a molded article from a mold by gripping the article and retracting it from the mold. While all of these methods are automatable, the apparatus are inapplicable to the removal of an endless film from the inner surface of a mold.
A need therefore exists for a film parting tool which will not damage a film to be removed from the inner surface of a mold. A need also exists for a film parting tool which is automatable, simple, effective and inexpensive.